Exploring the multifunctional quaternary Heusler alloys for energy conversion: Insights into optical and thermoelectric performance from first-principles

Abstract

The multifunctional quaternary Heusler alloys have emerged as a strong candidate for thermoelectric and optoelectronic applications, due to their simple crystal structure, tunable band gaps, and excellent transport properties. We report a thorough inspection on the optical and transport properties of a novel series of LiTiPtZ (Z = Al, Ga, and In) alloys for their photovoltaic and thermoelectric performance. The semiconductor nature of all three alloys is observed by the band structures, and the obtained band gaps are 1.01, 1.12 and 1.01 eV, respectively, suggesting the high absorption coefficient and optical conductivity in the visible and ultraviolet region, which demonstrates the possible use of these alloys in optoelectronic devices. The study of elastic and mechanical parameters ensures the mechanical stability of these alloys. To explore the thermoelectric performance, various parameters have been investigated. The maximum value of the figure of merit (ZT) is obtained for LiTiPtIn alloy (0.74) and a corresponding thermoelectric conversion efficiency of ∼15 %, highlighting its potential for high-temperature applications. The ZT values have also been compared with those of other comparable quaternary Heusler alloys and commercially available Bi₂Te₃-based materials.The outcome of this work is quite fascinating from a fundamental perspective, and it has immense significance in the practical realisation of alloys in photovoltaic and thermoelectric applications.